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10 Health Benefits of Probiotics, for the Gut, Brain and More

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Probiotic benefits - Dr. Axe

Whether you’re looking to skyrocket immune function, decrease disease risk or simply improve your overall health, probiotics can make a worthy addition to your daily routine.

What are probiotics? Nestled inside your gut are trillions of live microorganisms that make up the microbiome. Many of these bacterial cells are considered “good bacteria” and help support immune function, enhance nutrient absorption, and aid in the synthesis of key neurotransmitters and other compounds.

Probiotics are a type of organism that can help boost the amount of beneficial bacteria in your gut. They are found in probiotic supplements and fermented foods, including tempeh, natto, miso and kombucha.


Probiotics Benefits Begin in the Gut

The first and most overlooked reason that our digestive tracts are critical to our health is because 70 percent to 80 percent of our entire immune systems are located in our digestive tracts. That is an astounding percentage.

In addition to the impact on our immune systems, our digestive systems are the second largest part of the neurological system. It’s called the enteric nervous system and is located in the gut. This is why it’s called the second brain — the gut is responsible for creating 95 percent of the serotonin and may have significant impact on brain function and mood.

Many health issues, such as thyroid imbalances, chronic fatigue, joint pain, psoriasis and autism are connected with gut function, and yet it is not conventional practice for most in the field of medicine to address the gut first when treating such conditions.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, upward of 60 million to 70 million Americans are affected by digestive diseases. In addition, digestive disease and disorders cost the United States over $100 billion per year.

These statistics are staggering, yet poor gut health actually affects much greater numbers than these statistics illustrate because your digestive health affects every physiological system in your body. How is this such a complex system? Well, for one, the human microbiome contains 360 times more protein-coding genes than human genes themselves contain.

Every day, we’re exposed to toxins and inflammation-causing molecules from food and the environment that negatively impact digestion through pathways, such as leaky gut, known in the medical field as intestinal hyperpermeability. In leaky gut, the tight junctions that are supposed to keep disease-contributing compounds from leaving the digestive system are disrupted, allowing a lot of things through into the bloodstream that don’t belong there.

This process is linked closely to inflammation, which is at the root of most diseases, autoimmune conditions, inflammatory bowel diseases, thyroid dysfunction, nutrient malabsorption and mental issues (including depression and autism).

The secret to digestive health is all about balancing the good and bad bacteria in your gut. In a healthy life, consuming probiotic-rich foods and supplements daily is likely one feature of that balancing act.


10 Probiotic Benefits for Overall Health

Many studies have been conducted about the benefits of probiotics on a large number of health issues and conditions. Here, we will focus on the more thoroughly researched probiotics benefits, largely by sharing the results and data of meta-analyses on the subjects.

Then, several areas of emerging research on the benefits of probiotics are listed, reflected in small or pilot studies with promising results on probiotic benefits, as well as ways probiotics can be accessed.

1. Digestive Health

The first major benefit of probiotics is as a promoter of good digestive health. According to a meta-analysis conducted by Dalhousie University in Nova Scotia:

Probiotics are generally beneficial in treatment and prevention of gastrointestinal diseases… When choosing to use probiotics in the treatment or prevention of gastrointestinal disease, the type of disease and probiotic species (strain) are the most important factors to take into consideration.

Eating foods rich in good bacteria and using probiotic supplements may help provide protection from inflammatory bowel diseases, including ulcerative colitis and Crohn’s disease. The evidence is stronger, however, for an improvement in ulcerative colitis, while Crohn’s disease may not benefit as greatly. In addition, there is ongoing research studying the role of probiotics in gluten issues, including celiac disease.

Large bodies of evidence suggest that probiotics are effective against several forms of diarrhea, including antibiotic-associated diarrhea, acute diarrhea, traveler’s diarrhea, infectious diarrhea and other associated diarrhea symptoms. They also help with constipation relief. Probiotics have also been found in meta-analyses to reduce the pain and severity of irritable bowel syndrome (IBS) symptoms, aid in the eradication of H. pylori and treat pouchitis, a condition that occurs after the surgical removal of the large intestine and rectum.

2. Decrease in Antibiotic Resistance

The World Health Organization considers antibiotic resistance “one of the biggest threats to global health, food security and development today.” Bacteria become resistant to antibiotics due to the overuse of prescription antibiotics, lack of diversity in these medications and improper use of antibiotics

By using probiotics, it’s possible to help rebuild a poor variety of gut bacteria often seen after a course of taking antibiotics and prevent antibiotic-associated gut issues. In addition, probiotic supplements and foods may increase the effectiveness of antibiotics and help prevent the bacteria in your body from becoming resistant.

3. May Improve Mental Illness

The “second” brain of the gut has been a major point of research since scientists have discovered the importance of the gut-brain connection. A review in 2015 highlighted the complex interactions between the gut and brain, stating:

[Various gut-brain] interactions seem to influence the pathogenesis of a number of disorders in which inflammation is implicated, such as mood disorder, autism-spectrum disorders, attention-deficit hypersensitivity disorder, multiple sclerosis, and obesity.

The authors discuss the need for “pscyhobiotics” (probiotics that impact brain function) in handling the development of these conditions. This anti-inflammatory quality is what seems to interest researchers most. While no studies have been conducted in humans, early research suggests that, in animals, probiotic supplements may help alleviate symptoms of anxiety by reducing inflammation along this gut-brain connection.

Probiotics benefits seem to include a reduction in depression symptoms, according to a 2016 meta-analysis  the first review of its kind. Taking probiotics might also help reduce re-hospitalizations from manic episodes for those with manic depression.

A slightly more surprising result, however, seems to be the way that probiotics may impact some of the symptoms of autism. Autism and gut health have been discussed for some time, as patients with the disorder typically suffer from a large number of digestive issues. However, based on animal studies, it seems possible that altering the quality of gut bacteria might benefit not only the digestive system, but the abnormal behaviors in autism, too. In 2016, a case study of a boy with severe autism was reported. While being treated with probiotics for digestive problems, the patient spontaneously improved on the ADOS scale, a diagnostic rating system for people with autism. The score dropped from 20 down three points to a stable 17, and according to the report, ADOS scores do not “fluctuate spontaneously along time” and are “absolutely stable.”

Because of results like those above, human studies are currently underway to determine if probiotic supplements may improve not only the GI symptoms seen in autism, but also on “the core deficits of the disorder, on cognitive and language development, and on brain function and connectivity.”

4. Immunity Boost and Decrease in Inflammation

Both probiotics and prebiotics are a continuing topic of research regarding immunity. When used in conjunction, scientists refer to them collectively as synbiotics. One 2015 review on the subject stated, “We suggest that LAB and Bifidobacteria and novel strains [of probiotics] might be an additional or supplementary therapy and may have potential for preventing wide scope of immunity-related diseases due anti-inflammatory effect.”

Because chronic inflammation is at the root of many diseases and health conditions, the fact that probiotics exert this effect in the gut, where 80 percent of the immune system lies, is crucial. The immune-boosting benefits of probiotics seem to be particularly helpful for the quality of life of seniors. Currently, research is underway to test whether probiotics can “reduce inflammation and improve gut immune health in HIV-positive individuals” who haven’t yet undergone treatment.

Probiotics benefits - Dr. Axe

5. Healthy Skin

Many avenues of research have examined probiotics benefits for skin, especially in children. Meta-analyses have found that probiotic supplements are effective in the prevention of pediatric atopic dermatitis and infant eczema. The integrity of gut bacteria is also connected to the development of acne, although the way this happens is still unclear.

The skin benefits of probiotics seem also to be connected to the reduction of inflammation seen in healthy gut bacteria. L. casei, a particular strain of probiotic, “can reduce antigen-specific skin inflammation.” Indeed, research suggests that having a balanced gut environment has benefits for both healthy and diseased human skin.

6. Food Allergy Protection

Did you know that infants with poor gut bacteria are more likely to develop allergies over the first two years of life? The reason probiotics can help reduce food allergy symptoms, in particular, is most likely due to their abilities to reduce chronic inflammation in the gut and regulate immune responses — in adults as well as children.

7. May Treat Serious Diseases in Infants

Two dangerous diseases in newborns, necrotizing enterocolitis (NEC) and neonatal sepsis, may meet their match with well-designed probiotic supplements. Both of these conditions are common in premature babies and are most dangerous in low birth weight and very low birth weight infants. Research has confirmed that when a pregnant mother takes high-quality probiotics during pregnancy, her baby is significantly less likely to develop either NEC or sepsis, particularly when the baby is breastfed after birth (and mom is still taking the supplements) and/or when probiotics are added to formula. A probiotic supplement with multiple bacterial strains seems to be the most effective in these cases.

One review of probiotics benefits for necrotizing enterocolitis was bold enough to say, “The results confirm the significant benefits of probiotic supplements in reducing death and disease in preterm neonates. The … evidence indicate that additional placebo-controlled trials are unnecessary if a suitable probiotic product is available.” Regarding sepsis in developing countries (where it is overwhelmingly more common), a 2017 randomized, controlled trial claims that a large number of these cases “could be effectively prevented” if mothers are given a synbiotic (probiotic and prebiotic together) that contains the probiotic strain L. plantarum.

8. Lowering Blood Pressure

A large analysis reviewed available research and determined that probiotics help lower blood pressure by improving lipid profiles, reducing insulin resistance, regulating renin levels (a protein and enzyme secreted by the kidneys to lower blood pressure) and activating antioxidants. Researchers consider them valuable prospects in the treatment of high blood pressure because their side effects are generally minimal or nonexistent.

These effects are most pronounced in people who already have hypertension and improve when the subject consumes multiple probiotic strains for at least eight weeks or more in supplements containing 100 billion or more colony-forming units (CFUs).

9. Diabetes Treatment

Several large-scale studies and two meta-analyses have confirmed that probiotics should be a major consideration in determining natural remedies for diabetes. In a massive study involving almost 200,000 subjects and a total of 15,156 cases of type 2 diabetes, researchers confirmed that a higher intake of probiotic-rich yogurt reduced the risk of developing diabetes.

According to a 2014 meta-analysis, probiotics benefit diabetics by improving insulin sensitivity and decreasing the autoimmune response found in diabetes. The authors suggest that the results were significant enough to conduct large, randomized, controlled trials (the “gold standard” of scientific studies) to find if probiotics may actually be used to prevent or manage diabetes symptoms. Combining probiotics with prebiotics may also help manage blood sugar, particularly when blood sugar levels are already elevated.

10. May Improve Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) affects 80 million to 100 million people in the U.S. alone. Characterized by fatty buildup in the liver, NAFLD can eventually lead to cirrhosis, ending in liver failure or death for some patients.

A 2013 meta-analysis of studies on probiotics and NAFLD found that using probiotics can improve a number of important factors for patients with the disease, leading the study authors to state that: “Modulation of the gut microbiota represents a new treatment for NAFLD.”


Emerging Research: Benefits of Probiotics for Other Conditions

Cancer

Preliminary research suggests that certain probiotic strains may help prevent or slow/stop the growth of bladder and colorectal cancers. For colorectal/colon cancer, this effect may be increased by the use of prebiotics along with probiotic supplements.

One review on the current studies regarding cancer and probiotics stated that evidence does support that probiotics benefits may include an “anticarcinogenic action.” However, the quality of trials available was low, and more research must be done before a conclusion can be drawn for certain.

Dental Health

In a review of current evidence in 2009, European scientists determined that probiotic therapy could be a potential new option for dental health. The first randomized, controlled trials in humans suggest certain probiotic strains may aid in the prevention of cavities.

Urinary Tract Infections

Because of the way bacteria spread from the rectum to the vagina and urinary tract in women, probiotics have been a proposed remedy for urinary tract infection (UTI) in women. A 2012 review confirmed that probiotics seem to be effective in preventing recurrent UTIs, but more research is required before a determination can be made. The healthy strains of bacteria that help achieve this are also somewhat less common, which means proper treatment could be logistically complicated.

Rheumatoid Arthritis

Because poor gut health is related to autoimmune responses like those found in rheumatoid arthritis (RA), probiotics have been a proposed treatment option for the condition. Only a few studies have been conducted in humans, and only one testing L. casei 01, a particular probiotic strain, was able to find a decrease in RA inflammation and progression of the disease.

However, a 2003 pilot study and 2011 randomized, controlled trial both reported that RA activities remained unchanged, but the subjects treated with probiotics reported statistically significantly higher levels of “subjective well-being.” One suggested reason for this was that the trials were too short to establish changes in the observable changes in the internal earmarks of RA.

Kidney Stones

A number of species of Lactobacillus and Bifidobacterium probiotics might potentially help degrade oxalate, which cause kidney stones. Researchers are interested in these options because, unlike other medical treatments for kidney stones, probiotic bacteria survive in the gut.

However, human research must first be designed and conducted before it’s definitive that these bacteria could be effective. Scientists aren’t yet sure if the microbiome can be manipulated in such a way that will effectively decrease kidney stone risk.

Weight Loss

In the past, probiotics have been proposed as part of a weight loss diet. However, a 2015 meta-analysis looked at available randomized, controlled trials investigating this effect and determined that the studies did not seem to support this hypothesis, as body weight and BMI were not consistently reduced. The researchers did point out the need for better designed trials, because they were not convinced the results were based on well-designed science.


Probiotic Supplements and Beneficial Probiotic Strains

Nearly everyone can benefit from probiotic supplements, but they can be especially beneficial for those who aren’t getting at least a few servings of fermented foods in their diet.  Probiotics are widely available at health stores and pharmacies as well as online retailers, making it easier than ever to bump up the concentration of beneficial bacteria in your gut.

What is the best probiotic? While many people report beneficial effects from taking a probiotic supplement with many strains, you may want to dive a little further into what specific species can do. These are some of the beneficial bacteria you can expect to see on a high-quality probiotic supplement label to ensure you purchase good probiotics.

Some of the best probiotic strains include:

  • Bacillus coagulans
  • Saccharomyces boulardii
  • Bacillus subtilis
  • Lactobacillus plantarum
  • Bacillus clausii
  • Bifidobacterium bifidum
  • Bifidobacterium longum
  • Bifidobacterium breve
  • Bifidobacterium infantis
  • Lactobacillus casei
  • Lactobacillus acidophilus
  • Lactobacillus bulgaricus
  • Lactobacillus brevis
  • Lactobacillus rhamnosus
  • Lactic acid

In the search for the best probiotic on the market, there are several specific factors that you should keep in mind, including:

  • Brand: Be sure to always buy from a reputable retailer with plenty of positive customer reviews and look for a list of the best probiotic brands to ensure you’re getting the highest quality possible.
  • CFU count: Look for a probiotic with at least 10–20 billion CFU to maximize the potential health benefits.
  • Strain diversity: Probiotic supplements should contain a good mix of several different probiotic strains, each of which confers a unique set of benefits to health.
  • Live cultures: Ideally, the best probiotic supplement should be labeled “live and active cultures,” instead of “made with active cultures.” This is because some probiotics undergo heat treatment, which can kill off the beneficial strains of bacteria before they even reach your body.
  • Prebiotics: Just as important to gut health as probiotics are prebiotics, which help provide fuel for the beneficial bacteria in your gut. Select supplements with ingredients like flax seed, chia seed, pumpkin seeds and ginger to get in a good mix of prebiotics in addition to your supplement.
  • Stability: Certain types of probiotics require refrigeration to preserve their potency and ensure survival. Shelf-stable probiotics are a better choice because they are more likely to survive the journey through your digestive tract intact.

Probiotic dosage is measured in “colony forming units,” or CFUs. Ideally, you should aim for at least 5–10 billion CFUs per day for children and 10–20 billion CFUs each day for adults.


Precautions

Although probiotics are associated with a number of powerful health benefits, not all supplements are created equal. The best probiotic supplements should come from high-quality brands and should contain a good mix of different beneficial strains. Furthermore, steer clear of probiotic products that are packed with added sugar or extra ingredients, which can negate many of the health-promoting properties.

Some of the most common probiotics side effects include digestive issues like increased gas or bloating. To minimize the risk of potential side effects, start with a low dose and gradually work your way up to assess your tolerance. Most adverse side effects typically subside within a few weeks of starting probiotic supplementation.

If you have any underlying medical conditions or are taking any medications, you may want to consider consulting with your doctor before starting supplementation.


Final Thoughts

  • Probiotics can help boost the beneficial bacteria in your gut, which can improve several aspects of health ranging from improved immunity to increased nutrient absorption.
  • There are many different strains of probiotics, each of which boasts a unique set of benefits for health.
  • Look for a shelf-stable supplement that contains live cultures, prebiotics and a variety of different strains and avoid products with fillers, preservatives and added sugar.
  • You can also include several types of fermented foods as part of a balanced diet and healthy lifestyle to help optimize overall gut health.

Read Next: 17 Great Probiotic Foods You Should Be Eating


Josh Axe

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